A Global Marker Database for Phytophthora infestans

Abstract

A marker database was compiled for isolates of the potato and tomato late blight pathogen, Phytophthora infestans, originating from 41 locations which include 31 countries plus 10 regions within Mexico. Presently, the database contains information on 1,776 isolates for one or more of the following markers: restriction fragment length polymorphism (RFLP) “fingerprint” consisting of 23 bands; mating type; dilocus allozyme genotype; mitochondrial DNA haplotype; sensitivity to the fungicide metalaxyl; and virulence. In the database, 305 entries have unique RFLP fingerprints and 258 entries have unique multilocus genotypes based on RFLP fingerprint, dilocus allozyme genotype, and mating type. A nomenclature is described for naming multilocus genotypes based on the International Organization for Standardization (ISO) two-letter country code and a unique number. Forty-two previously published multilocus genotypes are represented in the database with references to publications. As a result of compilation of the database, seven new genotypes were identified and named. Cluster analysis of genotypes from clonally propagated populations worldwide generally confirmed a previously published classification of “old” and “new” genotypes. Genotypes from geographically distant countries were frequently clustered, and several old and new genotypes were found in two or more distant countries. The cluster analysis also demonstrated that A2 genotypes from Argentina differed from all others. The database is available via the Internet, and thus can serve as a resource for Phytophthora workers worldwide.

Occurrence and Distribution of Potato Pests and Diseases in Kenya

“…Kenya area (Meru and Timau), only genotype US-1 was found. This genotype was first delineated in the USA by Forbes et al (1998) and is thought to have displaced the Irish famine causing genotype sometime after the 1840s and to have been largely displaced itself in Europe and North America by migrations of other A1 and A2 genotypes in the 1970s (Fry et al 2009). Pule et al (2013) found only the US-1 genotype and its variants US-1.10 and US-1.11 in a 2007 survey of isolates originating from Burundi, Rwanda, Tanzania, Uganda, South Africa, Malawi, and Mozambique.…”

Self-Fertility in Two Clonal Lineages ofPhytophthora infestans

“…(B) Lane 1, US940486 (US-7 clonal lineage); lanes 2-6, single-zoospore isolates derived from US940486; lane 7, US940507 (US-1 clonal lineage); lanes 8-11, single zoospore isolates derived from US940507. Sizes are indicated in kilobasepairs (kb) as determined by Forbes et al (1998).…”

R/Avr gene expression study of Rpi-vnt1.1 transgenic potato resistant to the Phytophthora infestans clonal lineage EC-1

“…As previously noted, one isolate of the EC-1 clonal lineage of P. infestans that is abundant in in Peru, Ecuador, Colombia and Venezuela (Forbes et al 1997(Forbes et al , 1998Perez et al 2001;Delgado et al 2013) was able to overcome the resistance provided by Rpi-vnt1.1 and that its Avr-vnt1 gene was not expressed or was silenced Pel et al 2009;Pel 2010).…”